Home is where the hole is for residents of Laoying, who extol the insulating properties of their dwellings. Carved out of a section of Ming dynasty (1368-1644) wall, each home has walls up to 20 feet (six meters) thick. Along its immense length, the Great Wall system is dotted with many such walled villages as well as gates and crenellated towers where soldiers sent signals with smoke during the day and fire at night.